The lectin binding characteristic of the mucin found in colon cancer is different from that of normal colon. Similar changes in lectin binding are found in the mucins of certain non-malignant colonic epithelium with abnormal (and possibly premalignant) proliferative activity, including colonic polyps and transitional mucosa. Since lectins bind to the non-reducing termini of carbohydrate residues, the differences in lectin binding reflect changes in the carbohydrate structure of the respective mucins. In this proposal, lectin binding characteristics will be used to isolate mucin fractions specific for normal colon and colon cancer. An 125-I lectin binding assay and radioimmuno-assay will be developed to quantitate the appearance of cancer associated mucin in tissues and serum. The appearance of cancer associated mucin in colonic tissues (normal colon, colonic polyps, dysplasia, and the colons of patients with ulcerative colitis and familial polyposis) will be correlated with the risk of developing cancer. The appearance of cancer associated mucin in serum will be correlated with increasing tumor burden in known cancer patients. We will attempt to determine if the appearance of cancer associated mucin may be useful in predicting colon cancer in high risk patients (patients with inflammatory bowel disease, prior history of cancer or recurrent polyps, strong family history of colon cancer, etc.) and in the management of known colon cancer patients (i.e., to assess completeness of excision or recurrence). The purified mucins will also be characterized chemically, the carbohydrate side chains isolated and analyzed, the carbohydrate constituents of the lectin binding sites defined, and the enzymatic basis of the alteration studied.